DAVID GREENE, HOST:
Plants don't have ears, right? And if they can't hear you would assume that noise wouldn't matter much to them, which is why researchers haven't given much thought to the idea that noise might affect plants. But as Veronique LaCapra of St. Louis Public Radio reports, all of that may be about to change.
VERONIQUE LACAPRA, BYLINE: In northwestern New Mexico's Rattlesnake Canyon, gnarled juniper trees and pinyon pines dominate a landscape of high mesas and rough sandstone cliffs. Tucked in among the trees are thousands of natural gas wells, about a third of them pressurized by ear-splitting compressors.
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CLINTON FRANCIS: They run 24 hours a day, 365 days a year, with the exception of periodic maintenance, so they are going all the time.
LACAPRA: That's Clinton Francis of at the National Evolutionary Synthesis Center in North Carolina. Since 2005, he's been studying how Rattlesnake Canyon's birds respond to the compressors' nonstop racket.
FRANCIS: Black-chinned hummingbirds, for example, tend to prefer and settle in really noisy landscapes, and Western scrub jays tend to avoid these noisy areas.
LACAPRA: If the noise in the canyon is changing the way the birds behave. And that got Francis wondering. Maybe it's having an effect on plants, too. Take pinyon trees and scrub jays.
FRANCIS: We know that jays are really important seed dispersers for pinyon pine.
LACAPRA: The jays bury the seeds to snack on later, but inevitably, some get forgotten and grow into new pine trees. Francis already knew there were fewer pine seedlings at noisy sites. Was that because the noise was keeping the jays away from their pine nuts?
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LACAPRA: Francis set up motion-trigger cameras at both noisy and quiet sites, put out some pine seeds and waited. As he predicted, the jays were only stashing nuts at noisy sites.
FRANCIS: We only found them removing seeds on the quiet sites.
LACAPRA: But there was a twist. At the noisy sites, mice were gobbling up the seeds, not leaving any behind to sprout. So for the pine trees it looked the compressor noise was delivering a double whammy.
FRANCIS: We're just not getting as many seeds going into the seed bank in noisy areas, and the ones that do might be consumed by the mice that are there.
LACAPRA: But, Francis says, the effect of noise on the canyon's plants wasn't all bad. A flower pollinated by hummingbirds did better near the compressors. Remember, hummingbirds seem to like the noise - probably, Francis says, because it drives away the scrub jays that would otherwise eat the hummingbirds' eggs and young.
Francis just published his research in the British journal called Proceedings of the Royal Society B.
University of California Davis ecologist Gail Patricelli, also studies how gas-drilling noise affects birds - in her case, the greater sage grouse. She says as far as she knows, Francis's work is the first to show how noise affects plants.
GAIL PATRICELLI: You kind of hit yourself on the forehead and think, why didn't I think of that?
LACAPRA: I reached Patricelli on her cell phone at a remote field site in Wyoming. She says even there it's not quiet.
PATRICELLI: We hear airplanes. We hear roads going, you know, way off in the distance that are too far away to see and yet you can still hear them, because sound travels much, much further than a lot of the other types of disturbance. And so it's just an enormous land area that's impacted by noise, and we know remarkably little about what that noise does to the ecosystem.
LACAPRA: But it seems likely that for long-lived species like the pinyon pines in Rattlesnake Canyon, the effects of noise may continue to reverberate long after the sound of the compressors has gone silent.
For NPR News, I'm Veronique LaCapra.
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